Solid state lighting (“SSL”) devices are used in a wide variety of products and applications. For example, mobile phones, personal digital assistants (“PDAs”), digital cameras, MP3 players, and other portable electronic devices utilize SSL devices for backlighting. SSL devices are also used for signage, indoor lighting, outdoor lighting, and other types of general illumination. SSL devices generally use light emitting diodes (“LEDs”), organic light emitting diodes (“OLEDs”), and/or polymer light emitting diodes (“PLEDs”) as sources of illumination, rather than electrical filaments, plasma, or gas. FIG. 1A is a cross-sectional view of a conventional SSL device 10a with lateral contacts. As shown in FIG. 1A, the SSL device 10a includes a substrate 20 carrying an LED structure 11 having an active region 14, e.g., containing gallium nitride/indium gallium nitride (GaN/InGaN) multiple quantum wells (“MQWs”), positioned between N-type GaN 15 and P-type GaN 16. The SSL device 10a also includes a first contact 17 on the P-type GaN 16 and a second contact 19 on the N-type GaN 15. The first contact 17 typically includes a transparent and conductive material (e.g., indium tin oxide (“ITO”)) to allow light to escape from the LED structure 11. In operation, electrical power is provided to the SSL device 10a via the contacts 17, 19, causing the active region 14 to emit light.
FIG. 1B is a cross-sectional view of another conventional LED device 10b in which the first and second contacts 17 and 19 are opposite each other, e.g., in a vertical rather than lateral configuration. During formation of the LED device 10b, a growth substrate (not shown), similar to the substrate 20 shown in FIG. 1A, initially carries an N-type GaN 15, an active region 14 and a P-type GaN 16. The first contact 17 is disposed on the P-type GaN 16, and a carrier 21 is attached to the first contact 17. The substrate is removed, allowing the second contact 19 to be disposed on the N-type GaN 15. The structure is then inverted to produce the orientation shown in FIG. 1B. In the LED device 10b, the first contact 17 typically includes a reflective and conductive material (e.g., silver or aluminum) to direct light toward the N-type GaN 15. A converter material 23 and an encapsulant 25 can then be positioned over one another on the LED structure 11. In operation, the LED structure 11 can emit a first emission (e.g., blue light) that stimulates the converter material 23 (e.g., phosphor) to emit a second emission (e.g., yellow light). The combination of the first and second emissions can generate a desired color of light (e.g., white light).
SSL or LED devices similar to the SSL device 10a and the LED device 10b of FIG. 1A and FIG. 1B, respectively, can be included in LED devices having additional components. FIG. 1C is a partially schematic isometric view of a conventional SSL or LED device 30a. As shown in FIG. 1C, the LED device 30a includes a controller 32, a first LED 34a, a second LED 34b and a third LED 34c (collectively, LEDs 34). The LED device 30a can be connected to a power source (not shown) through the contacts 36. The power source and the controller 32 provide electrical signals to produce emissions from the LEDs 34 through a first channel 35a, a second channel 35b and a third channel 35c. 
In many conventional lighting systems, the LEDs 34 are monochromatic emitters that produce either red, green or blue light. For example, the first LED 34a can be red, the second LED 34b can be green and the third LED 34c can be blue. By controlling the signals sent to the individual LEDs 34, the LED device 30a can produce a variety of different colors. In one example, a mixture of similar intensity or brightness from the LEDs 34 can produce an overall emission that is generally white. However, most chromaticities generally require unique brightness levels for each of the LEDs 34. Devices similar to the LED device 30a are often constructed at the chip level with multiple LED devices 30a on one chip. Providing individual control circuits for each individual LED device 30a increases manufacturing complexity and cost. Other LED devices have multiple individual LEDs that can be controlled on a single channel, thereby allowing a single controller to operate a much larger number of LEDs 34.
FIG. 1D is a partially schematic isometric view of another conventional LED device 30b including a first LED package 38a having a plurality of first LEDs 34a, a second LED package 38b having a plurality of second LEDs 34b and a third LED package 38c having a plurality of third LEDs 34c. The LED device 30b further includes a controller 32 and external contacts 36. Similar to the LED device 30a shown in FIG. 1C, the first LEDs 34a can be red, the second LEDs 34b can be green and the third LEDs 34c can be blue. The first channel 35a, the second channel 35b and the third channel 35c control a plurality of individual LEDs 34 for each LED package 38a, 38b, 38c. By varying the signals to the individual LED packages 38a, 38b, 38c the LED device 30b can also produce a variety of chromaticities of light.
Generally, the controller 32 can provide a finite number of control signals that each correspond to a potential intensity or brightness of the individual LEDs 34. Each combination of brightness levels from the LEDs 34 corresponds to a different chromaticity. Accordingly, the LED devices 30a and 30b are capable of producing a finite variety of chromaticities of light that is limited by the combinations of available control signals. Additionally, if the overall intensity or brightness of the emitted light is lowered, the available chromaticities can be substantially limited. Accordingly, there exists a need for light emission systems having an increased fidelity over a broad brightness range.